For physical-layer security, key reconciliation procedures are needed to correct key differences that can arise as a consequence of independent noise at the two ends of a reciprocal link. We assume either a random link in a mobile environment or use reconfigurable antenna elements to randomize the channel, such that it allows for frequent key generation. We apply LDPC codes to reconcile the key...

While computational security algorithms usually reside in upper protocol layers and rely on the assumption of limited processing capabilities of a potential eavesdropper, physicallayer key generation aims at providing secrecy in the more information-theoretic sense, as introduced by Shannon [?]. Thus, by sharing a previously known secret key, such as a one-time pad, two legitimate users, Alice ...

In this paper, we consider secure device-to-device (D2D) direct communication in cellular networks for wiretap channel. We assume that D2D transmitter sends its data to desired D2D receiver by reusing frequency resources originally allocated to the cellular link transmission between a base station (BS) and a cellular user. When there is a single eavesdropper (ED) in wiretap channel, we propose ...

ACKNOWLEDGEMENTS Let me start at the beginning and thank my parents. They provided a glorious childhood for me and my siblings in a small town in northern Utah. They are extremely diligent and humble, and they raised their family to appreciate traditional Christian values. No matter where my career leads, if I can only duplicate their success with their children, then I will have no regrets. Th...

T his thesis studies physical layer security for multi-user multiple-input multiple-output (MIMO) wireless systems. Due to the broadcast nature of the physical medium, wireless multi-user communications are very susceptible to eavesdropping, and it is critical to protect the transmitted information. Security of wireless communications has traditionally been achieved at the network layer with cr...

—Cognitive Radio (CR) is a novel technology that promises to solve the lack of spectrum by allowing secondary users to use licensed band, so that they can coexist with primary users without causing interference to their communications. With the development of CR, extending to the level of network, cognitive radio networks (CRNs) emerge as the times require. Nowadays the operational aspects of ...

A wireless network of multiple transmitter-user pairs overheard by an eavesdropper, where the transmitters are equipped with multiple antennas while the users and eavesdropper are equipped with a single antenna, is considered. At different levels of wireless channel knowledge, the problem of interest is beamforming to optimize the users’ quality-of-service (QoS) in terms of their secrecy throug...

Relaying is one of the useful techniques to enhance wireless physical-layer security. Existing literature shows that employing full-duplex relay instead of conventional half-duplex relay improves secrecy capacity and secrecy outage probability, but this is at the price of sophisticated implementation. As an alternative, two-path successive relaying has been proposed to emulate operation of full...

We present experimental data on message transmission in a free-space optical (FSO) link at an eye-safe wavelength, using a testbed consisting of one sender and two receiver terminals, where the latter two are a legitimate receiver and an eavesdropper. The testbed allows us to emulate a typical scenario of physical-layer (PHY) security such as satellite-to-ground laser communications. We estimat...

The use of physical layer methods for improving the security of wireless links has recently become the focus of a considerable research effort. Such methods can be used in combination with cryptography to enhance the exchange of confidential messages over a wireless medium in the presence of unauthorized eavesdroppers, or they can be used to enable secrecy in the absence of shared secret keys t...